RE: opp layer query apis (was RE: omap3 pm: dependency between opp layer and cpufreq)

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> -----Original Message-----
> From: Gopinath, Thara
> Sent: Tuesday, June 08, 2010 7:29 AM
> >>-----Original Message-----
> >>From: Menon, Nishanth
> >>Sent: Tuesday, June 08, 2010 9:45 AM
> >>> -----Original Message-----
> >>> From: Gopinath, Thara
> >>> Sent: Friday, June 04, 2010 3:35 PM
> >>
> >>> Slightly off the topic but considering we are discussing opp layer
> here, I
> >>> do not find API's
> >>> that take the OPP type (OPP_MPU or OPP_L3) and voltage/frequency as
> >>> parameters and returns back the associated frequency/voltage. I do not
> >>> want to get the opp table entry every time I do this. Any chance of
> >>> introducing this in the framework? I could send a patch for the same.
> >>Am curios on the usage that combination of
> >>opp_find_freq_exact
> >>opp_find_freq_ceil
> >>opp_find_freq_floor
> >>
> >>and opp_get_freq, opp_get_voltage is unable to cater to? Would be
> interested
> >>in seeing a patch for the same.
> 
> Ok here is the need. Let us suppose I know the opp type (OPP_MPU,
> OPP_L3 ...) etc and the frequency and I need to get the voltage. Today I
> have to do the following
> 	struct omap_opp *opp =
> opp_find_freq_exact/opp_find_freq_floor/opp_find_freq_ceil(type, freq);
> 	u32 volt = opp_get_voltage(opp).
> 
> As a user of opp layer it would be much simpler for me to do
> 	opp_get_volt(type, freq, exact/ceil/floor) as  I really do not care
> about the opp struct at all.
The intent was we are not always sure what exact behavior the caller desires.

Option1: (currently implemented)
Opp_get_volt(opp_find_freq_exact/opp_find_freq_floor/opp_find_freq_ceil(type, 
freq)

Option2:
Opp_get_volt_freq_exact(freq);
Opp_get_volt_freq_ceil(freq);
Opp_get_volt_freq_floor(freq);

The intent is if we don't really care about the opp structure, choose the 
nature of the search and plug it straight to get_volt.

> 
> Now let us suppose I have the opp type and the voltage I need to put the
> vdd associated with it to. Today there is no way to retrieve the frequency
> from the opp layer.


Why would we want to do this?

> 
> Again as a user of the opp layer I would like to have an API
> 	u32 freq = opp_get_freq(type, volt)

A voltage could be linked to 1 or more frequencies. OPP layer functions 
based on some sort of unique identifier. We aligned earlier this year(jan if 
I recollect), that frequency is the common unique identifier, is there a 
Reason that this is not good enough?

Regards,
Nishanth Menon
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